Question

Two small identical spheres having charges + 10µC and –90µC attract each other with a force of F newton. If they are kept in contact and then separated by the same distance, the new force between them is-

• A. F/6
• B. 16F
• C. 16F/9
• D. 9F

Answer 1

Answer: (C)

16F/9

Answer 2

F = ........(i)

charge on each when contact is made

= = $\frac { 10 + ( - 90 ) } { 2 }$= –40µC

\ New force F¢ =

\ = $\frac { 40 \times 40 } { 10 \times 90 }$ = $\frac { 16 } { 9 }$

\